1. Field of the Invention
This invention relates to casting and more specifically to methods and apparatus for cost effective metal casting.
2. Description of the Prior Art
Conventional methods of automated metal casting often use metal filter grates, placed by hand, at the interface of the riser tube and the mold. This approach requires hand labor and introduces potential impurities to the process. When the molten metal is depressurized the introduction of oxygen into the riser tube forms metal oxides that form layers within the riser tube changing the process parameters with every casting and introducing further impurities into the process.
When casting softer metals such as aluminum the steel filter screen in the casting sprue may be cut by a die during removal of the sprue, thus shortening the useful life of the die. The presence of the filter screen within the sprue may also serve as a heat conductor enhancing the cooling of the sprue before cooling of the main casting improving the likelihood of voids in the casting.
What is needed is a technique to minimize hand labor in semi-automated metal casting, reduce the likelihood of introducing impurities, stabilize the casting process and improve control of the casting process.